This invention relates to a marine jet drive apparatus having a non-steering jet reverse deflector apparatus pivotally mounted over a trimmable power jet steering means and particularly to a unique mounting of reverse jet deflector apparatus over the steering means.
Jet drive apparatus for small recreational boats and the like has been developed as alternative drives to the conventional outboard motor and/or inboard-outboard stern drive units. Jet drive apparatus generally includes a pump means for establishing and directing water through a jet nozzle to develop a powerful jet stream which is emitted from the aft end of the boat and establishes forward motion. Steering is accomplished by lateral deflection of the jet stream to either side of a center line position and, thereby, creates a steering force. The jet deflection may conveniently be provided by use of a steering nozzle or deflector forming the aft end of the jet nozzle. The steering deflector pivots about a vertical axis and provides a simple and reliable means of deflecting of the jet for steering purposes. To shift between forward, reverse and neutral, a reverse gate or deflector means is conventionally employed and connected to a suitable remote shift control means. The deflector means is mounted to be selectively positioned over the end of the jet deflector and operable to deflect the jet stream downwardly and forwardly of the boat and thereby create a reverse or backward thrust on the boat. By positioning of the reverse deflector means in an intermediate position, the reverse thrust forces will just balance the forward thrust forces thereby establishing a neutral or stationary boat drive position. Movement of the gate upwardly will uncover the steering deflector thereby increasing the forward thrust forces while simultaneously reducing the reverse thrust forces and effecting the forward movement of the boat. Reverse positioning of the deflecting means further reduces the forward thrust forces while increasing the reverse thrust forces and results in a consequent reverse force movement of the boat.
In conventional practice the steering deflector is also pivoted on a horizontal axis for trim positioning of the drive jet relative to the boat for optimum propulsion efficiency. The reverse gate is mounted on the steering nozzle or deflector to move therewith. As a result, the relative position of the deflecting means overlying the steering nozzle is maintained during trim positioning of the nozzle and the relative strength of the forward and reverse drive or thrust forces does not change. This maintains a neutral drive setting, as the trim setting can vary. This, however, requires that the gate positioning mechanism accommodate the various nozzle movements associated with steering and trim positioning of the nozzle. Generally, flexible push-pull type cables which have a high degree of flexibility such as required by the steering nozzle movement are employed as part of the gate positioning mechanism. Such cables have also been widely employed in conventional propeller drives and are, therefore, known and accepted in the marine trade. However, push-pull cables have certain inherent disadvantages particularly when employed in marine applications. The high moisture environment outside the board creates significant rusting problems. Such cables are also subject to bending and kinking, making operation difficult and unreliable under such conditions, and are subject to breakage. Outside the boat, direct mechanical linkage systems, which include rigid links and interconnected pivot and swivel joints, can be more readily and reliably provided and are therefore desirable.
If the reverse gate means, for example, is directly mounted to a fixed portion of the jet drive apparatus such as the pump housing and made of a sufficient width to completely cover the steering deflector for all trim positions, the flexible cable can be replaced by a fixed linkage such as employed in the trim setting system. However, with the deflection or gate means positioned on the relatively immovable portion of the apparatus, each change in trim position of the steering deflector requires a new positioning of the reverse deflection means to establish the neutral, or other desired drive position. Thus, as the steering deflector is trimmed, its orientation with respect to the jet drive housing changes and, therefore, also changes with respect to the reverse deflection means mounted on such housing. This creates an undesirable condition and may create a highly hazardous condition upon starting of the engine if the reverse deflection means and steering deflector positions do not create a neutral drive state.
The prior art systems have, therefore, employed a gate mounted on the steering deflector in combination with push-pull cable systems for coupling of the gate to a remote shift control means. The push-pull cable systems, of course, require special care and servicing to compensate for the adverse effects of the high moisture environment, as previously discussed. There is, therefore, a significant need for a more reliable revising drive control which can be economically produced and serviced.